Problem with my Stihl 034AV

[EnglishWoodsman]

For some reason my chain has problems being pulled around when switched off, when I'm trying to sharpen it. It's not tough to go round, like it's tight, but it won't go at all, like it's jamming. There's nothing wrong with the chain brake and when switched on, the chain goes around fine. If I loosen the chain even a bit, then the chain sags off the bar, and I know it's too loose. The right "tightness" is when it starts refusing to move by hand. Any help? Thanks!

[Texas-Jim]

Check the cage bearing on the sprocket, and the sprocket. If sprocket is worn bad enough it can do that.

[EnglishWoodsman]

Hey, thanks for the reply.

The sprocket is new, fitted yesterday (I thought it might be the cause) and the needle cage is in good condition, having only been replaced a little before Christmas.

There is an issue with the chain tensioner, the cylindrical cog that pulls the guide bar pin back and forth appears to be narrower than the gap in the housing where the cog under the screw itself meets it, so it rocks back and forth. As such, the tightness is never completely secure. However, I can't understand why that would cause the chain to jam when I try and shift it when sharpening.

[skooter]

Is the chain on backwords It happens to the best of us.

[HolmenTree]

Check the guide  bar's sprocket nose tip. Might be seizing up or one of the tiny roller bearings popped out and is jammed between the bar rails.

[limbwood]

are you sure its the correct size sprocket, 3/8 chain will bind up on .325 sprocket

[EnglishWoodsman]

Haha, I've only done that once (so far) when I first got the new chain! Thankfully that's not it.

[EnglishWoodsman]

This bar actually doesn't have a sprocket, my dad has just told me (technically his chainsaw but I use it more).

[EnglishWoodsman]

It was jamming on the old sprocket, which the chain, until recently, went around just fine.

[HolmenTree]

Ok so you have a new drive sprocket  (rim I'm sure) and a new chain. Check them again and let us know if they're both either .325 pitch or 3/8" pitch. Rim an chain have to match.

Now you did say the guide bar has no sprocket nose,  so it's a armor tip. These bars require the chain to be properly tensioned with a little sag in the chain. You don't tension them lightly  snug like you would on a sprocket nose bar.
I'm guessing that's your problem right there.

[EnglishWoodsman]

Hey, thanks! Yes the sprocket was the same, 3/8ths.

The fact it is meant to be loose is enlightening. I was not aware of that nor have we been taught to be aware of this at college!

[Texas-Jim]

Did you throw the chain? Lot of times if chain comes off it can damage the drive links.

[EnglishWoodsman]

Nah that hasn't happened, thankfully!

[DelawhereJoe]

Have you tried a different bar and chain on the saw yet perhaps the old bar has many burs on it that its hanging up or there could be a dent thats pinching the chain.